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Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge toast The Queen at the Queen's Birthday Garden Party at the Orangery, Lazienki Park on the first day of their official visit to Poland on July 17, 2017, in Warsaw, Poland.

The Duke and Duchess of Cambridge attended a reception in Poland on Monday where Prince William read out a letter from Queen Elizabeth II praising good bilateral ties, at the start of a two-country goodwill trip intended to underscore Britain's intention to maintain friendly relations with the European Union after Brexit.

From Warsaw's airport, the royal couple was driven in a motorcade to meet President Andrzej Duda and the first lady at the Presidential Palace for lunch. They visited the palace gardens and after lunch took a short stroll in front of the palace and were greeted by a huge crowd waving British and Polish flags.

"I am so happy that I saw this beautiful couple," said Helena Wozna, 63, who was in the crowd. "Prince William shook my hand. I'm happy I came here."

William and his wife Kate then met with World War II veterans at the museum to the 1944 Warsaw Uprising against the Germans, and traveled to a business center where they met with representatives from Polish and British business. Hundreds of thousands of Poles live and work in Britain, strengthening business ties.

The Polish hosts have said this is a visit of "respect and friendship" that shows relations remain strong.

At an evening reception, William read out a letter from his grandmother, Queen Elizabeth II, in which she praised bilateral ties and recalled the visit that she and the Duke of Edinburgh made to Poland in 1996. He also delivered a brief speech during the reception, which was held in Lazienki Park in honor of the 91-year-old queen.

William, second in line to the throne, has taken on more public duties in recent years as the queen gradually eases up on her schedule due to advancing years.

On their first official visit to Poland, William and Kate were accompanied by their children, Prince George, who turn 4 Saturday, and Princess Charlotte, 2. The children are expected to draw wide attention on a trip being characterized by the British media as part of a charm offensive to soften Britain's Brexit diplomacy. Warsaw's Belvedere Palace, where they are residing during the visit, has had playground equipment installed.

On arrival, the Duchess was wearing an Alexander McQueen white skirt and jacket and carrying Charlotte, who was dressed in a pink flowered sleeveless dress. William was wearing a dark suit and George was in short trousers and a shirt.

On Tuesday, the royals will travel to the Baltic coast where they will visit Stutthof, a World War II Nazi German concentration camp. They will also tour the historic city of Gdansk, where they will see a replica of Shakespeare's theater and meet the former president, Lech Walesa, who was instrumental in bringing about the end of communism in Poland. On Wednesday, they head to Berlin.